Hollow plastic containers with an external very thin coating of low permeability to gases and vapors through plasma-assisted deposition of inorganic substances and method and system for making the coating

ABSTRACT

A method, composition and system for coating an external surface of containers and in particular, plastic containers, provides for low permeability to gases and vapors. The coating applied to the external surface of the containers is very thin and is comprised of one or several inorganic substances or layers of substances. For example, the coating can include silica which is bonded to the external surface of the container. This coating will be flexible and can be applied regardless of the container&#39;s internal pressure or lack thereof. The coating will firmly adhere to the container and possess an enhanced gas barrier effect after pressurization even when the coating is scratched, fractured, flexed and/or stretched. Moreover, this gas barrier enhancement will be substantially unaffected by filling of the container.

BACKGROUND OF THE INVENTION

This invention relates to pressurized plastic containers that haveenhanced barrier performance and methods to provide said containers andto the coatings. The enhanced barrier performance is obtained byapplication of inorganic coatings to the external surface of thecontainer. The coatings exhibit enhanced adhesion relative to prior artcoatings.

DESCRIPTION OF THE BACKGROUND ART

Plastic containers currently comprise a large and growing segment of thefood and beverage industry. Plastic containers offer a number ofadvantages over traditional metal and glass containers. They arelightweight, inexpensive, nonbreakable, transparent and easilymanufactured and handled. However, plastic containers have at least onesignificant drawback that has limited their universal acceptance,especially in the more demanding food applications. That drawback isthat all plastic containers are more or less permeable to water, oxygen,carbon dioxide, and other gases and vapors. In a number of applications,the permeation rates of affordable plastics are great enough tosignificantly limit the shelf-life of the contained food or beverage, orprevent the use of plastic containers altogether. Shelf-life is the timeneeded for a loss of seventeen percent of the initial carbonation of abeverage.

It has been recognized for some time that a container structure thatcombines the best features of plastic containers and more traditionalcontainers could be obtained by applying a glass-like or metal-likelayer to a plastic container, and metallized plastic containers. Forexample, metallized potato chip bags have been commercially availablefor some time. However, in a number of applications, the clarity of thepackage is of significant importance, and for those applicationsmetallized coatings are not acceptable. obtaining durable glass-likecoatings on plastic containers without changing the appearance of thecontainer has proven to be much more difficult.

A number of processes have been developed for the purpose of applyingglass-like coatings onto plastic films, where the films are thensubsequently formed into flexible plastic containers. However,relatively few processes have been developed that allow the applicationof a glass-like coating onto a preformed, relatively rigid plasticcontainer such as the PET bottles commonly used in the U.S. forcarbonated beverages, and heretofore no process has been developed thatallows the application of a glass-like coating onto the external surfaceof a plastic container that is sufficiently durable to withstand theeffect of pressurization of the container, retain an enhanced barrier togases and vapors subsequent to said pressurization, and not affect therecyclability of the containers. Pressurized beverage containerscurrently comprise a very large market world-wide, and currentlyaffordable plastics have sufficiently high permeation rates to limit theuse of plastic containers in a number of the markets served.

Such pressurized containers include plastic bottles for both carbonatedand non-carbonated beverages. Plastic bottles have been constructed fromvarious polymers, predominant among them being polyethyleneterephthalate (PET), particularly for carbonated beverages, but all ofthese polymers have exhibited various degrees of permeability to gasesand vapors which have limited the shelf life of the beverages placedwithin them. For example, carbonated beverage bottles have a shelf-lifewhich is limited by loss of CO₂. While this limitation becomesincreasingly important as the size of the bottle is reduced, because ofthe increasing surface to volume ratio, small containers are needed formany market applications, and this severely limits the use of plasticbottles in such cases. Generally, based upon this surface to volumeratio, as a bottle becomes smaller, carbonation retention in thebeverage becomes more difficult.

For non-carbonated beverages, similar limitations apply, again withincreasing importance as the bottle size is reduced, on account ofoxygen and/or water-vapor diffusion. It should be appreciated thatdiffusion means both ingress and egress (diffusion and infusion) to andfrom the bottle or container. The degree of impermeability (describedherein as “gas barrier”) to CO₂ diffusion and to the diffusion ofoxygen, water vapor and other gases, grows in importance in conditionsof high ambient temperature. An outer coating with high gas barrier canimprove the quality of beverages packed in plastic bottles and increasethe shelf life of such bottles, making small bottles feasible, and thisin turn presents many advantages in reduced distribution costs and amore flexible marketing mix.

Some polymers, for example PET, are also susceptible to stress crackingwhen they come in contact with bottle-conveyor lubricants used in bottlefilling plants, or detergents, solvents and other materials. Suchcracking is often described as “environmental stress cracking” and canlimit the life of the bottle by causing leaks and prevent damage toadjacent property. An impermeable outer surface for plastic bottles, andprevent damage to adjacent property which resistsstress-cracking-inducing chemicals, will extend the shelf life ofplastic bottles in some markets.

Another limitation to shelf life and beverage quality is often UVradiation which can affect the taste, color and other beverageproperties. This is particularly important in conditions of prolongedsunshine. An outer coating with UV absorbing properties can improve thequality of such beverages and make plastic bottles much more useableunder such conditions.

Additional functionality can be incorporated into the inorganic coatingby incorporating visible light absorbing species, rendering the plasticcontainer cosmetically more appealing.

An additional benefit of the present invention is ease of recycling.Prior art barrier enhancing coatings generally are organic in nature andare much thicker than the coating of the present invention.Consequently, when post-consumer scrap containing containers coated withprior art organic coatings are recycled, significant deterioration inthe appearance and properties of the plastic occur. In contrast, becauseof the inert nature and thinness of the coatings of the presentinvention, the coated containers can be processed in any conventionalrecycling system without modification of the process.

Moreover, haziness in recycled articles can occur when large sizedparticles are used in a coating. However, such a haze is avoided in thepresent invention because relatively small particles are used as will bedescribed. Moreover, the coating is acceptable for food contact andtherefore will not adversely affect the recycling effort when ground ordepolymorized in the recycling process.

Along the lines of recycling, the present invention provides for amethod of recycling coated plastic which has results heretoforeunattainable. In particular, separation of coated and uncoated plasticsis unnecessary whereby modifications to existing recycling systems areunnecessary or whereby extra process steps (separating coated bottlesfrom uncoated bottles) can be avoided. Moreover, it is possible toproduce a transparent plastic from coated plastic while avoiding theabove-noted problem of haziness in the final recycled product. While thepresent invention can be used in recycling many types of plastic, it iscontemplated that this invention can be used with plastic articles, suchas containers or bottles and more particularly, with plastic beveragebottles. Bottle-to-bottle recycling remains unaffected with the presentinvention.

Recycling in the instant invention can be carried out in both a chemicalprocess and a physical process. The plastic subjected to recyclingprocesses can be molded or extruded. Even if a coated plastic isinitially introduced in the recycling process, the coating of thepresent invention will not interfere with the downstream injectionmolding or blow molding.

Finally, the cost of applying a coating to the outside of a bottle,which has a gas barrier which significantly increases the shelf-life ofbeverage container in that bottle, and/or which significantly reducesproduct spoilage of beverage container in that bottle, and/or whichsignificantly reduces product spoilage due to UV radiation, and/orvirtually eliminates environmental stress cracking, and/or provides aspecific color, must not add significant cost to the basic package. Thisis a criterion, which eliminates many processes for high gas barriercoatings, because plastic bottles are themselves a very low cost, massproduced article. Affordability implies in practice that the cost of thecoating must add minimal or no increase to the cost of the whole packageand in fact, the cost can be less.

A coating on the outside of plastic bottles must be capable of flexing.When bottles are used for pressurized containers, the coating preferablyshould be able to biaxially stretch whenever the plastic substratestretches. In addition it is preferable that the coating be continuousover the majority of the container surface. However, in the presentinvention, unlike prior art devices, the continuous coating is notessential because of the high level of adhesion of the inorganic coatingto the surface of the plastic container. In other words, even though thecoating of the present invention may be non-continuous because ofscratches or fractures therein, for example, the coating will continueto effectively adhere to the substrate such as an underlying plasticbottle. The present invention can therefore provide an effective gasbarrier even if the surface is highly fractured. A high gas barrier of1.25×greater than a similar uncoated container can be obtained with thepresent invention and this barrier can even be 1.5× or preferably2×greater.

Adhesion is particularly important in the case of carbonated beverages,since the CO₂ within the bottle exerts some or all of its in-bottlepressure on the coating. This pressure can rise to above 6 bar, exertingconsiderable forces on the coating/plastic interface. The coating mustalso resist scuffing, normal handling, weathering (rain, sun climate,etc.), and the coating must maintain its gas barrier throughout thebottle's useful life.

There are several plasma-enhanced processes which apply an external,inorganic coating to a range of articles, which in some cases includesbottles. Many of the processes are targeted to provide coatingproperties which are quite different, and far less onerous than high gasbarrier bottle coatings. Such processes target, for example, abrasionresistance, where the coating continuity is not a major factor, sincethe coating can protect the microscopic interstices. Other processestarget cosmetic or light-reflection properties and some processes have apure handling protection role. Often the substrate does not flex norstretch and the article itself is higher priced than plastic bottles sothat cost is not a benefit of the design. In some cases, the substrateallows far higher coating temperatures than those allowed by PET, themost common plastic-bottle material. Such processes do not, in general,provide the coating continuity, adhesion, flexibility needed for highgas barrier coatings, nor do they provide a solution to the otherproblems relating to high gas barrier coatings, described above.

Prior art also exists for gas barrier processes for bottles, but thelack of commercially available, coated bottles for pressurizedapplication is due to the fact that these processes lack the desirableattributes described above and fail to provide a coating with adequateadhesion, continuity and/or flexibility under high in-bottle pressure ora coating which avoids recycling problems, or the low cost necessary tomake the coating affordable.

U.S. Pat. No. 5,565,248 to Plester and Ehrich describes a method forcoating containers internally. However, external coatings require fargreater adhesion than internal coatings, because in-bottle pressure actsagainst external coatings, and internal coatings are not subject to thesame handling and/or abrasion in use. For these, and other reasons,coating bottles externally differs from coating them internally and thepresent invention is therefore substantially different.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide anouter coating or layer for a container such as a heat sensitive plasticbottle, and particularly for the non-refillable bottles used forcarbonated beverages.

It is a further object of the present invention to provide a coating anda system and method for coating which can provide an external glass-likecoating that is flexible, durable and possess sufficient adhesion towithstand the effects of pressurization without significant loss ofenhanced barrier properties.

An additional object of the present invention is to provide anexternally coated container which will avoid environmental stresscracking such as when the container comes into contact with conveyorlubricants during filling, detergent, cleaners or solvents or similarsubstances during its life cycle. Such lubricants can include 409™, MeanGreen™ or other commercially available cleansers or lubricants, etc.

Yet another object of the present invention is to provide a lightercontainer and a system and method for making the container whereby anamount of plastic utilized in making the container as compared to aconventional container can be reduced without adversely effecting orwhile improving the gas barrier effectiveness of the container.

It is another object of the present invention to provide a coating thatcomprises an inorganic oxide layer on the external surface of a plasticcontainer, the inorganic oxide layer being further distinguished bybeing comprised of greater than or equal to 50 and up to but less than100% SiOx (x=1.7 to 2.0).

Another object is to provide a coating which possesses sufficientadhesion to the external surface of the plastic container so that thebarrier enhancement provided by the inorganic oxide layer is notsubstantially reduced upon pressurization of the container to a pressurebetween 1 and 100 psig.

A further object of the present invention is to provide a method forapplying an inorganic layer as described above, the method resulting ina robust inorganic oxide layer that provides an effective level ofbarrier enhancement to the plastic container and does not result insignificant physical distortion of the container.

It is a further object of the present invention to provide a system andmethod for manufacturing a container whereby the aesthetic appeal of thecontainer will be enhanced by applying a colored inorganic layer thatfurther contains visible-light absorbing species.

Yet another object of the present invention is to provide a coating fora container with UV absorbing capabilities.

Still another object of the present invention is to provide a containerwith a colored or clear coating which can easily be recycled withoutsignificant or abnormal complications to existing recycling systems.

Another object of the present invention is to provide a system andmethod for inexpensively manufacturing an externally coated container.

Yet another object of the present invention is to provide a method whichthe thickness and composition of the applied coating on a container canbe rapidly and easily determined and whereby process control andinsurance of enhanced barrier performance can be obtained.

A further object of the present invention is to provide a method todetermine the condition of the surface of a plastic container at leastwith regards to its suitability for applying glass-like coatings.

Another object of the present invention is to provide a high gas barrierwhich considerably increases the shelf life of the containers such asplastic bottles and to provide the containers with good transparency soas not to affect the appearance of a clear plastic bottle.

Yet another object of the present invention is to provide a containerwith enhanced barrier performance both when the container walls flex orstretch under pressure and when the walls are indented.

Still another object of the present invention is to provide a containerwith adequate durability and adhesion during working life, when theouter surface of the container is subjected to environmental conditionssuch as severe weather, rubbing, scuffing, or abrasions (for example,during transportation) or when the outer coating is subjected tointernal pressure and with the ability to maintain a gas barrier whileremaining stressed by in-bottle pressure throughout the container'suseful life.

Also, another object of the present invention includes the ability toenable coating to heat sensitive plastic containers with coatingmaterials, which can only be vaporized at very high temperatures withoutan acceptable increase in the plastic's temperature and which mustremain in many cases below 60° C.

The foregoing and other objects of this invention are fulfilled by amethod, apparatus and process control procedure for plasma-assisteddeposition of a very thin, typically 10-100 nm, inorganic outer surfacecoating on a container such as a plastic bottle using inorganicsubstances.

Although not bound to any particular theory, the formation of a highlyadherent, dense, continuous coating may be achieved in the presentinvention by producing a high energy plasma which further provides goodcoating adhesion by enabling penetration of the coating beneath thesurface of the plastic. This penetration is additionally assisted by abiasing energy using RF or HF. Formation of a dense coating is furtherenhanced by the ability to coat under conditions of high vacuum(generally in range 10⁻³ to 10⁻⁵ mbar) which avoids unwanted gasmolecules being incorporated into the coating and is still furtherenhanced by the ability to cause the reaction components of the coatingto react stoichiometrically.

Furthermore, the method described herein enables surface pretreatmentfor the activation of the plastic surface by forming free radicals whichcan react with and attach to the coating and enhance adhesion beforecoating begins. The method further includes surface cleaning, wherenecessary. The method identifies the need to apply surface activationduring pretreatment, and to control this, since activation can becounter productive by damaging the surface. The method also describesmeans of inspecting the bottle surface for coating suitability andidentifies factors which lead to the preference to coat containers(particularly PET bottles) quickly, or immediately, after molding. Themethod describes means of degassing the plastic, so as to avoid vaporemission from the plastic surface which interferes with the coating, andreduces its adhesion or density.

The form of deposition provides for an approach angle of plasmaparticles to the surface which does not exceed 70° to the vertical, soas to enhance coating adhesion. It also provides for mixtures ofsubstances to be deposited, and particularly for the trace of addition(up to 50%) of metal ions into silica, which increases silica's gasbarrier for pressurized packages. The form of deposition also enablesheat sensitive containers to be coated without significant temperaturerise, and at all times maintaining a bottle temperature well below 60°C.

While this angle of 70° to the vertical was noted above, it is importantto recognize that there may be certain situations where this limitationwould not apply. For example, if bottles or containers surrounded avapor source, then no limitation on the angle would be desired. In otherwords, plasma particles could be moving 360° from their source if thebottles or containers to be coated surrounded the source. Alternatively,if two parallel conveyors were provided for moving the bottles orcontainers past a given source with the source being between theconveyor lines, then plasma particles could also move 360° from thissource in order to reach the bottles or containers on both conveyorlines. Other situations are envisioned whereby the angle would not belimited to 70°.

The method enables mixtures and layers of substances to be applied whichcan be chosen for their color, or UV-absorbing properties, or additionalgas barrier properties. Further, the method enables coatings, such assilica, which are fully transparent and clear, and would therefore notaffect the appearance of an otherwise clear bottle. The coatingmaterials are inert and remain solid when the plastic bottle is meltedfor recycling.

The method for coating the outer surface of a container according to thepresent invention comprises the steps of (1) conveying the containers toa loading/unloading station where they are placed into a holding crate(“holder”); (b) conveying the holder/containers into a “tool” stationwhich applies in-bottle antennas and seals the containers with caps,which enable the inside of the container to stay under pressure duringcoating and provide for the containers to be gripped, rotated andreleased at the appropriate parts of the coating cycle; (c) locatingholder/containers in an evacuation cell which brings theholder/containers to the pressure of a vacuum cell; (d) conveyingholder/containers into the vacuum cell to a container loading/unloadingtable and raising holder/bottles to permit the containers to be grippedand located in a conveyor chain; (3) conveying containers whilecontinuously rotating them in a vertical position within the vacuum cellthrough stages, which enable degassing of plastic, then pretreatment toclean/activate the container surface, then container base coating; (f)conveying containers while continuously rotating them in a horizontalposition within the vacuum cell to enable the container sidewall to becoated; (g) returning the coated containers to the containerloading/unloading table where they are replaced in the holder; (h)returning holder/containers to the evacuation cell where they arebrought back to normal atmospheric pressure; (i) conveying theholder/containers to the “tool” station where the antennas and caps areremoved; (j) conveying holder/containers to the containerloading/unloading station where the coated containers are removed fromholder and replaced by uncoated containers so that the cycle can berepeated.

Within the vacuum cells, a plasma at very low pressures is created usinga conventional electron gun. While the gun itself is known, the methodof using this gun in the present invention is new as will be describedbelow. Trace metals can be added to a silica coating by sacrificialerosion of the electron gun. The solid deposit will stoichiometricallyand on-surface react with the reactive gas to ensure that surplus gasmolecules cannot be build into the coating, thus avoiding porosity. Thecoating is at high vacuum to reduce interference of ambient gasmolecules with the coating process and to avoid gas molecules beingbuilt into the coating, causing porosity. A very thin coating, generallybelow 100 nm is deposited on the container. Optionally, RF and HF energyis used to bias the coating particles and an in-cell antenna and RF orHF or DC energy is optionally used to create a pretreatment plasmawithin the vacuum cell. The plastic container is degassed to avoid vaporemerging from the plastic which can interfere with the coating process.Multiple plasma-making systems can be used whenever more than one solidmaterial is needed for the coating process.

An apparatus for performing the above-mentioned method steps comprises:(a) a holder and means of loading containers into it; (b) a cap whichseals the container opening and which incorporates a screw driver-typeslot and quick-snap-in-release connection for gripping, releasing andturning the containers; (c) an antenna which can be erected inside thecontainer, maintain a minimal gap with the walls of the containerwithout touching the walls, and can be orientated to face in the desireddirection either magnetically or by gravity; (d) means of insertingantenna into the containers and applying the cap; (e) means of sealingholder/containers in a cell which can either be pumped down to coatingpressure so as to enable the holder/containers to enter the vacuum cell,or can be repressurized to enable holder/containers to exit the vacuumcall; (f) means of conveying holder/containers into the vacuum cell andmeans for gripping the containers in a conveyor system which runs withinthe vacuum cell; (g) a vacuum cell with an internal conveying systemwhich conveys the containers, while continuously rotating them, first invertical position, then in horizontal position; (h) a plasma-makingsystem having a conventional electron-gun and coating-materials that areto be deposited; (i) a biasing system using RF or HF energy and applyingit to the in-container antenna, and use of this system both forpretreatment and for densifying the coating by biasing the coatingparticles; (j) an optional in-vacuum cell mounted antenna which cancreate a pretreatment plasma by using RF or HF or DC energy; and (k)means of introducing a gas or mixture of gases into the vacuum cell.

These and other objects of the present invention are fulfilled by asystem for coating an external surface of a container wherein thecontainer on pressurization possess a gas barrier at least 1.25×greaterthan a similar uncoated container, the system comprising:

a vacuum cell, pressure within the vacuum cell being reduced as comparedto ambient pressure;

means for supplying containers to and withdrawing containers from thevacuum cell; and

at least one source for supplying a coating vapor to the externalsurface of the containers in the vacuum cell, the coating vapor from theat least one source depositing a relatively thin coating on the externalsurface of the containers,

whereby bonding between at least a portion of the relatively thincoating deposited on the container and the external surface of thecontainer occurs.

Moreover, these and other objects of the present invention are fulfilledby a system for coating an external surface of a container wherein thecontainer on pressurization has enhanced environmental stress crackresistance, the system comprising:

a vacuum cell, pressure within the vacuum cell being reduced as comparedto ambient pressure;

means for supplying containers to and withdrawing containers from thevacuum cell; and

at least one source for supplying a coating vapor to the externalsurface of the containers in the vacuum cell, the coating vapor from theat least one source depositing a relatively thin coating on the externalsurface of the containers,

whereby bonding between at least a portion of the relatively thincoating deposited on the container and the external surface of thecontainer occurs.

In addition, these and other objects of the present invention arefulfilled by a plastic container having an inorganic oxide coating on anexternal surface thereof, the coated plastic container possessing a gasbarrier of at least 1.25×after pressurization as compared to a similarlypressurized uncoated container.

These and other objects of the present invention are also fulfilled by amethod for coating a plastic container comprising the steps of:

introducing said container into a vacuum cell;

applying an inorganic composition to an external surface of thecontainer in the presence of at least one reactive gas and atsub-atmospheric pressure; and

removing the container from the vacuum cell.

In addition, these and other objects of the present invention arefulfilled by a method for producing recycled content plastic comprisingthe steps of:

providing a batch plastic, at least a portion of the plastic having acoating thereon;

grinding the plastic to produce flakes; and

melt extruding the flakes.

A method for producing recycled content plastic fulfills these and otherobjects of the present invention with the steps of:

providing at least some coated plastic;

depolymerizing said at least some coated plastic; and

re-polymerizing said depolymerized plastic.

Moreover, these and other objects of the present invention are fulfilledby a plastic container having an exterior inorganic coating that has anequivalent gas barrier and reduced weight compared to a plasticcontainer of similar surface area and volume and without said exteriorinorganic coating.

In addition, these and other objects of the present invention arefulfilled by a method of extending shelf life of a plastic containercomprising the steps of:

providing a plastic container, the plastic container having an inorganiccoating on an external surface thereof;

filling the plastic container with a pressurized beverage;

sealing the plastic container after the step of filling;

preventing escape of pressurized gas from the plastic container, thecoating being utilized in prevention of escape of the pressurized gas;

holding the pressurized gas within the container for a longer timeperiod than a similarly sized and shaped container without the inorganiccoating, the inorganic coating being utilized in the holding of thepressurized gas; and

permitting at least one of flexing and stretching of the inorganiccoating without substantially affecting the step of holding.

Still yet these and other objects of the present invention are fulfilledby a device for coating containers, the device comprising:

an electron gun;

a receptacle for holding material, the electron gun vaporizing at leasta portion of the material held in the receptacle; and

means for conveying containers through an area having vapor produced bythe electron gun vaporizing the material, the vapor being deposited onthe containers to thereby coat an exterior of the containers.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will be more readily understood from the detaileddescription given hereinbelow and the accompanying drawings, which aregiven by way of illustration only and thus are not limitative of thepresent invention, and wherein:

FIG. 1 is a schematic illustration of the basic process and itparameters;

FIG. 1A is a schematic illustration similar to FIG. 1, but showing thereceptacle 3 and a supplemental receptacle positioned on a support 19;

FIG. 1B is a schematic illustration similar to FIG. 1, but showing amodified form of the coating chamber;

FIG. 2A shows the in-bottle antenna and bottle-capping arrangementbefore insertion of the antenna;

FIG. 2B shows a cross-section of the in-bottle antenna andbottle-capping arrangement of FIG. 2A after insertion of the antenna;

FIG. 2C is a cross-sectional view showing a modified form of anin-bottle antenna prior to insertion;

FIG. 2D is a cross-sectional view similar to FIG. 2C after insertion ofthe in-bottle antenna;

FIG. 3 is one embodiment of a coating machine in accordance with thepresent invention;

FIG. 4 shows the handling of bottles, holder, caps, antennas,air-displacing collars of the present invention;

FIG. 5A shows a system for conveying bottles first vertically, thenhorizontally while bottles are continuously rotated;

FIG. 5B shows a sectional view of the bottle bar taken along line V—V ofFIG. 5A;

FIG. 6A is a view of bottles moving past plasma-making and coatingsources;

FIG. 6B is a side sectional view taken along line VI—VI of FIG. 6A;

FIG. 7A shows a scanning electron microscope (SEM) photograph of a PETbottle surface after in-plastic light molecular weight components havediffused to the surface;

FIG. 7B is a photograph similar to FIG. 7A showing a refillable PETbottle surface;

FIG. 7C is a similar photograph to FIG. 7A before this diffusion hastaken place;

FIG. 7D is a similar photograph to FIG. 7C before this diffusion hastaken place, but at a ½ magnification of only 10,000 times;

FIG. 8A shows an SEM photograph of the surface of a PET bottle, whichhas been stretched when the bottle was pressurized to a pressure of 6.5bar, and whose coating has good adhesion and good coverage in spite ofthis stressing;

FIG. 8B is a similar photograph to FIG. 8A, but the view at 4 timesmagnification (20,000 times);

FIG. 8C is a similar photograph to FIG. 8A of a coating which has pooradhesion and stretchability;

FIG. 8D is a similar photograph to FIG. 8C of a coating which has pooradhesion and stretchability, but at 100 times magnification;

FIG. 9 is a graph showing improvements in gas barrier factor withincreasing content of Zn or Cu;

FIG. 10 is a flow chart illustrating the steps of physical recycling;and

FIG. 11 is a flow chart illustrating the steps of chemical recycling.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Coatings with good adhesion to a surface of a container, good gasbarriers, and providing the necessary stretchability and flexibility canbe produced by the process and systems of the present invention.Throughout the present specification, a container or bottle 10 will bedescribed. While this container will generally be described withreference to a plastic bottle, any suitable container can be treated bythe method and system of the present invention. Accordingly, soft drinkbottles of various sizes, other food containers or any other suitablecontainer can be treated using the disclosed method and system.

FIG. 1 shows a source 1 used as typical evaporation and plasma-makingsystem for this present invention. A conventional, water-cooled electrongun 2 is used to convey energy to a conventional receptacle 3, whichholds the coating solids 4. This receptacle 3 is constructed of amaterial suitable for melting and evaporating the particular coatingsolid chosen, and must be both inert and resistant to the temperaturenecessary for generating the quantities of vapor needed. For example,for evaporating silicon, carbon has been found to be a suitablematerial. The receptacle 3 is suspended from a receptacle holder 5,which is water cooled or cooled by other methods.

By using these conventional components (i.e., electron gun 2 andreceptacle 3, and by varying the position of the electron gun 2 relativeto the horizontal surface of the receptacle 3, the proportion of energyavailable for plasma-making and evaporation can be adjusted. Forexample, in position A, a large portion of the energy is available forplasma-making, while in position B, almost all energy is used forevaporation and hardly any plasma is formed. The degree of energy to thesource 1 is adjusted by the voltage V to give the particular depositionrate on the external bottle surface 6 which enables coating solids 4,after evaporation, to deposit and react completely (i.e.,stoichiometrically) with the gaseous substance 7 (or mixture ofsubstances) introduced into the coating chamber 8, thus ensuring that nosignificant amounts of unreacted gas can be occluded within the coating9. For example, in one of the preferred embodiments, which uses siliconas coating solid 4 and oxygen as gaseous substance 7, deposition ratesonto the coating surface of 2 to 20 nm/s can give fully transparentcoatings, with virtually x=2 in SiO_(x), while avoiding surplus oxygen(or air) and maintaining high vacuum in the coating cell (in region of10⁵ mbar to 10³ mbar).

For producing good gas barrier results, it is beneficial to ensure thatan on-surface reaction between coating solids 4 and gaseous substance 7takes place after coating solids 4 have been deposited and formed asolid lattice, since the gaseous substance 7 then densities the coating9 by reacting into the solid lattice. The distance H between a surface 6of a container 10 and the receptacle 3 is important when avoiding thecoating solids 4 which react with the gaseous substance 7 before thecoating solids 4 are deposited onto the container surface 6. Equally,the condition of the coating solids 4 is important in securing maximumon-surface reaction. When these coating solids 4 are to be oxidized onthe container surface 6, as in case of silicon, large chunks with lowoxidized surface areas give best results. A distance H is chosen so asto give optimal use of source 1 (thus enabling it to coat as manybottles 10 as possible) while at the same time providing acollision-free path (thus limiting reaction prior to the containersurface 6). Distance H is dependent on vacuum and deposition rate, butgenerally in region 0.3 m to 1 m. Also, increasing distance H, withinthe limitations described, enables high-energy plasmas to be created atsource 1 without heat-damaging the container 10.

It is usually important to ensure that the individual particles of thecoating solids 4 strike the container surface 6 at high speed andtemperature, so that the first molecular layers of coating 9 break intocontainer surface 6 thus forming an embedded foundation for the coating9, which in turn helps the adhesion of the coating to the container 10and the coating's flexibility, stretchability and resistance to theinternal pressure generated with soft drink bottles, for example (whichacts onto the bottle surface 6 and stresses the coating 9). High-energyplasma-generation (determined by position of electron gun 2, voltage Vand distance between electron gun 2 and receptacle 3) is an importantparameter, together with the coating angle α. A coating angle α inregion 0-70° helps provide adequate adhesion, while angles aboveapproximately 70° give poorer gas barrier results, since in such a case,the coating-solids 4 impinge at an angle to the surface which reducessurface impact.

Biasing energy, provided by locating an antenna 11 inside the bottle orcontainer 10 and connecting it to an RF or HF source, also helps toimprove the adhesion and density of coating 9 by accelerating anddirecting the ionized portion of the plasma toward the bottle surface 6.Depending on the material of bottle 10, biasing energies of up to 2000 Vimprove gas barrier, while normally these are in region 100-800 V.Excessive bias voltage can be detrimental by overheating and damagingthe bottle surface 6. The antenna 11 must remain oriented in line withsource 1 and means of achieving this, while bottle 10 rotates, aredescribed below.

Rotation of bottle 10 enables the bottle 10 to be coated over its entiresurface at a high rate of deposition of coating solids 4 while allowingtime for reaction with gaseous substance(s) 7. When coating thesidewall, the rate of deposition of coating solids 4 onto the part ofthe surface of bottle 10, which is directly opposite source 1 and whichis the only surface receiving significant deposition of coating solids4, can be adjusted by rotating bottle 10 at an adequate rate, so thatthis deposition comprises only a few molecular layers. These molecularlayers can be easily reacted with gaseous substance(s) 7, thus achievingthe desired criterion of on-surface reaction with a solidified deposit,since this helps provide the required dense, continuous coating whichgives good gas barrier. Also, since that part of the surface of bottle10, which is not opposite source 1, can continue to react while notreceiving deposition of coating solids 4, this procedure brings thewhole 360° circumference of bottle 10 into the deposition/reaction cycleand reduces coating time. Therefore, correct setting of rotation rate(R) helps secure full reaction at optimal coating rate conditions.Conditions of high vacuum (e.g. 10⁻⁵ mbar to 10⁻³ mbar) and very thincoatings (usually below 100 nm) help to provide coatings which arecontinuous and exhibit no cracks, if stretched under pressure or flexed,when studied under high magnification using an scanning-electronmicroscope.

Small or trace additions of certain metals in silicon dioxide and othercoatings can increase gas barrier. Such metals include Ag, Al, Ca, Cr,Cu, Fe, K, Mg, Mn, Na, Ni, Sn, Ti, and Zn, and are added to form aproportion of metal in coating 9 of 0.01 to 5%. For example, suchadditions to a coating 9 mainly composed of SiO₂ increase the gasbarrier by a factor of 2, or more. Such metals are added either toreceptacle 3, or are provided by the sacrificial erosion of the electronemitting plate or shield 12 of the electron gun 2, this beingconstructed out of the desired metal, or mixture of metals.

Alternatively, as shown in FIG. 1A, a separate receptacle 16 can beprovided for holding a source 16′ of metals. The receptacles 3 and 16can be supported on the floor of the coating chamber 8 as shown in FIG.1, or on a support 19 as shown in FIG. 1A or at any suitable location.The electron gun 2 can act on the materials 3′, 16′ in both respectivereceptacles 3, 16 or two separate electron guns can be provided. Also,the spacing between the receptacles 3, 16 can be relative close as shownin FIG. 1A or they can be further apart or the spacing can be varied.

In FIG. 1B, an alternative embodiment of the coating chamber 8 is used.Instead of using in-bottle antennas 11 or coating cell antenna 14 or inaddition to these antenna 11, 14, an external biasing antenna 28 isused. This antenna 28 is for biasing during coating. Of course, this isseparate to the already shown out-of-bottle antenna 14 for pretreatment.While not indicated in FIG. 1B, appropriate means are provided forholding and/or transporting the containers 10. While a continuous orsemi-continuous process for treating the bottles or containers 10 isdiscussed below, it should be evident that the present invention is alsoapplicable to batch processing.

While not shown in FIGS. 1, 1A or 1B, an automatic source for supplyingthe material to receptacle 3 and/or 16 can be provided. These materialscan be supplied as a rod or other solid structure or in any other form.It is contemplated that material in the receptacle 3 will be in solidform and in particular will be in a chunky or nonpowder form. Byminimizing the surface area of this material, detrimental affects ofoxidization can be avoided. The material in the receptacle 3 (and 16, ifpresent) will be a source of vapor in the coating chamber when actedupon by the electron gun 2. This vapor will be deposited on the bottlesor containers 10 as will be described below. It should be noted thatwiring 17 is indicated in FIG. 1A attached to the receptacle 16. Thiswiring 17 can be used to supply current to the receptacle 3 and/or 16 asdescribed in U.S. Pat. No. 5,565,248, if so desired. Of course, suchwiring can be omitted.

When the shield or plate 12 is used as a source, the degree of erosioncan be approximately controlled by adjusting distance D betweenreceptacle 3 and electron gun 2, and by the degree of cooling applied toplate or shield 12 by the means for cooling 15. This means for cooling15 can cool one or both of the electron gun and the plate or shield 12.Water cooling or any other suitable cooling can be provided by thismeans for cooling 15. The other main variable affecting erosion of plate12 is the voltage V applied to the electron gun 2, but this is normallyadjusted independently according to the plasma generation andevaporation rate requirements.

The choice of coating solids 4 and gaseous substance 7 depends on theprocess criteria (cost, coating color, degree of gas barrier necessarysize of bottle and particularly the type of plastic used in the bottle).Good gas barriers have been obtained by procedures described above bymeans of on-surface reaction of silicon with oxygen, giving SiO_(x)where x is greater than 1.8, and normally insignificantly less than 2and thus, glass-like transparent. Also, the blending-in of significantproportions (i.e. about 1-50%) of Ti and/or Al and/or B and/ormono-valent metals (such as Na K) and/or divalent metals (such as Mg,Ca) have increased gas barrier in certain conditions, whereby in case ofCa, Mg, Na or K these can be introduced in the form of a salt (e.g. CaF₂or MgF₂), and in case of B the introduction can be in the form of thesolid oxide. Alternatively, the process conditions described can providegood gas barriers, using metals (such as Ag, Al, Cr, Ge, Ti, Sn, An,Zr), or mixtures of metals, instead of silicon, and reacting these withgaseous substances T other than oxygen, such as N, S or halogens. Tosuch metallic coatings, silicon may be beneficially added. It iscontemplated that the coating contains 0.01 to 50% of one or moreelements selected from the group consisting of Li, Na, K, Rb, Cr, Mg,Ca, Sr, Ba, Ti, Al, Mn, V, Cr, Fe, Co, Ni, Zn, Cu, Sn, Ge and In.

Use of metals and other gaseous substances also enables coloredcoatings, or UV-absorbent coatings (by choosing the reactantsappropriately). More than one layer, each layer comprising a differentcomposition, can also be beneficial, particularly when producing coloredcoatings, since combining colored and transparent layers enables a goodgas barrier to be obtained with minimum thickness of colored coating,thus enhancing recyclability. When more than one type of substance isused as coating solid 4 it is often necessary to provide more than onesource 1, since differences in vapor pressure between substances canresult in fractionation and uncontrolled proportions of each substancein the coating 9.

Surface pretreatment, aimed at activating bottle surface 6 by formingfree radicals on the surface, assists in providing continuous coatingsand good adhesion, leading to durable gas barriers. Such pretreatment ispossible using a gaseous pretreatment substance 13 (which can often bethe same as the gaseous substance 7 or substances) and at same cellpressure conditions. The pretreatment time is adjusted so as to lightlyactivate the surface only, since heavy activation is accompanied bydegradation of the bottle surface 6, in turn leading to poor adhesionrather than the improved adhesion, which is the aim of the pretreatmentprocess.

Pretreatment is carried out either by using the in-bottle antenna 11with RF or HF energy to create a gas-plasma on bottle surface 6, or byconnecting a coating cell antenna 14 to a DC or HF or RF source andcreating a plasma within the entire cell.

It is desirable that the bottle surface 6 is degassed to remove absorbedmoisture and low molecular weight materials. This is achieved by holdingthe bottle 10 in a vacuum for a period of 5-180 s. The time required fordegassing is dependent on the condition of bottle 10 (in relation to itstemperature and absorbed vapors). Bottles 10 blown immediately afterblow molding can be degassed relatively quickly, and location of coatingprocess beside a blow molder is desirable. Also, degassing can beaccelerated using energy, by applying either RF or HF to the internalantenna 11, or DC/RF/HF to the coating cell antenna 14, or from an IRsource located near bottle surface 6, not shown.

For certain compositions of coating 9, it is desirable to apply thecoating on a bottle 10, which during the coating process has an internalpressure significantly higher than the cell pressure. This givesimproved gas barrier by enabling coating 9 to relax/contract when bottle10 is not under pressure while also enabling coating 9 to resistcracking due to stretching when bottle 10 comes under pressure in normaluse.

Some plastic surfaces, particularly those of PET, which is a polymermost commonly used in plastic bottles, deteriorate after blow moldingdue to the migration to the surface of low molecular weight components.It is important to determine the quality of the bottle surface 6 priorto coating. Under scanning electron microscope, these migratingcomponents can be observed on bottle surface 6, and an important qualitycontrol can thus be applied.

FIGS. 7A and 7B show a typical PET bottle surface after surfacediffusion of low molecular weight components and FIGS. 7C and 7D show,by way of comparison, a PET bottle surface soon after the blow molder,when no diffusion has taken place. For quality control, it has also beendemonstrated that Rutherford-Back-Scatter (RBS) is able to determine thethickness of very thin coatings (e.g. 50 nm) and also their composition,the latter being important when coating with more than one solidcomponent. X-ray fluorescence also can be used to measure coatingthickness, and, because this is a relatively simple process, X-rayfluorescence can be applied as an in-line quality control system after acoating machine. Finally, observing the surface of coated bottles 10under a scanning electron microscope after these bottles 10 have beensubjected to gas pressure, enables a first indicator of coatingperformance, since coatings 9, with poor gas barrier performance, havetendency to crack/peel.

FIGS. 8A and 8B show the surface of a coated PET bottle after the bottlewas subjected to an in-bottle pressure of over 6 bar and part of thecoating was deliberately scratched to enable its continuous coverage andits adherence, even close to the damage, to be observed. For comparison,FIGS. 8c and 8D show a coating with poor surface adhesion, wheredistinct peeling and splitting in the coating has been caused by thestretching of the PET.

FIG. 2 shows an antenna and bottle capping arrangement, as an example.Other similar arrangements achieving the same result are possible. A cap20 incorporates a sealing ring 21, a threaded portion 22, a snap-in,quick-release connector 23 and a contact ring 24 for the biasing voltagewhich can be applied either by RF (radio frequency) or HF (highfrequency). The contact ring 24 has an electrical connection 25 whichhas a sliding contact with the antenna stem 26. The antenna stem 26 ismounted in a bearing 27, which is in turn mounted inside the cap 20, andis free to rotate within the cap. The antenna 30 has the antenna stem26, hinged arms 31 a, 31 b, light antenna segments 32 a, 32 b and aheavy antenna segment 33. Hinged arm 31 b also acts as antenna for thebase of bottle 10 when extended. At the base of the antenna stem 26 is aball bearing 34, which can rotate freely, and is pressed downward by aspring 35 and a pin 36. When antenna 30 is outside the bottle 10, theantenna segments 32, 33 are folded against the antenna stem 26, due tothe action of the spring 35, as shown in FIG. 2A. Pin 36 has a base stop37 and a swivel 38 to which the hinged arm 31 b and the antenna segment32 b are connected. As pin 36 moves up/down, hinged arm 31 b and antennasegment 32 b extend outward or fold against antenna stem 26. When theantenna 30 is inserted into the bottle 10, the ball bearing 34 is forcedto compress the spring 35 and this extends the hinged arm 31 b outwardlyfrom the antenna stem 36, which erects the antenna 30 so that all itssegments 32 a, 32 b and 33 approach the walls of bottle 10. A gapbetween walls of bottle 10 and antenna 30 is maintained which is asclose to the walls of bottle 10 as possible, but without touching, andis in practice between 3 and about 15 mm.

Cap 20 is screwed onto the threaded finish (mouth) of bottle 10 and thegaseous content of bottle 10 is thereby sealed by sealing ring 21. Atool (not shown), enters the connector 23 in cap 20 and provides thescrew driver action for turning the cap 20 to screw it onto bottle 10.The same tool holds the bottle 10 (until released by connector 23) andmakes contact with the RF/HF biasing voltage on contact ring 24. Ofcourse, a snap-in, quick-release connector or other known connectionsfor cap 20 instead of a screw connection could also be used. When thebottle 10 is held and turned horizontally, the heavy antenna segment 33ensures that the antenna 30, which has no contact with the walls ofbottle 10, is able to maintain a position facing vertically downwardsand therefore acts as means for orienting the antenna to generally facethe at least one source during coating. When antenna 30 is orientatedwhile bottle 10 is rotated in vertical position, use of a magneticmaterial in antenna segment 33 and an external magnet, appropriatelypositioned, enable the antenna 30 to face in the correct direction.Accordingly, this magnet will act as magnetic orientating means fororienting the antenna when the longitudinal axis of the container isgenerally vertically oriented.

The principle demonstrated by FIGS. 2A and 2B can also be applied to amulti-segment design. In such a multi-segment design, where a pluralityof antenna-segments 32 a, 32 b, 33 and hinged arms 31 a, 31 b enable afolding arrangement which can pass through the finish of bottle 10 andcan be erected within bottle 10 giving a 360° C. antenna-coverage of itswalls. In such a case, the need for antenna orientation is eliminatedand a greater portion of the bottle is subject to biasing energy,enabling shorter coating times in certain applications.

Moreover, apart from using the antenna 11 or 30 a back plate 18 in thevacuum cell can be provided as indicated in FIG. 1. The bottles orcontainers 10 are positionable between this back plate 18 and the source1. When used, this back plate can result in the insertion of an antenna11 or 30 into bottles 10 unnecessary. This can speed the overallprocess, reduce the need to have an inventory of antennas and canprovide other benefits.

Alternatively, a portion or all of the vacuum cell 50 or coating chamber8 can be used as an antenna. For example, the back plate 18 can beomitted and the ceiling alone or the ceiling and some of the walls orthe entire chamber 8 can be used as the antenna. Other arrangements arealso possible.

Another potential for avoiding the antennas 11 or 30 comprises providinga magnetic source within the vacuum cell 50 as generally indicated bynumeral 58 in FIG. 3. The number of magnetic sources 58 and therelocation within vacuum cell 50 can readily be varied. This magneticsource 58 acts as a means for generating a magnetic field within thevacuum cell 50 wherein the field directs the coating vapor.

This magnetic source could alternatively be used to selectively directthe coating vapor going to the bottle surface, thereby avoiding some orall of the need to mechanically rotate or translate the bottles. Thismagnetic source will therefore act as means for generating a field todirect the coating vapor.

While still using an in-bottle antenna, FIGS. 2C and 2D show anotherpossible type of antenna 69. This antenna 69 is straight and thereforeis more easily inserted into and removed from the bottle or container10. This antenna 69 simply runs as a straight “peg” from the cap towithin a few millimeters of the base of the bottle or container 10. Thisantenna 69 also simplifies the operation because no pivoting,orientation, folding-out to fit the walls of the bottle or container 10,etc. are needed. While antenna 69 is shown as being generallycoextensive with the longitudinal axis of the respective bottle orcontainer 10, it is contemplated that a skewed orientation is alsopossible. In other words, antenna 69 would be angled relative to thelongitudinal axis of the bottle or container 10. In such an angledposition, the antenna 69 may or may not intersect the longitudinal axisof the bottle or container 10.

Alternatively, a corkscrew antenna could also be used. This antennawould be screwed into the bottle or container 10, yet would be closer tothe sidewalls than the straight antenna 69 without touching thesesidewalls. Other possible antennas are, of course, also possible.

It is normally desirable to avoid coating the threaded finish of abeverage bottle, because this may affect the closure performancecharacteristics and because this can come in contact with the beverageand perhaps the mouth of the consumer. Although all of the coatings usedin this invention are safe in contact with food, it is nonethelessdesirable to restrict beverage contact to the main bottle material. Cap20 covers the finish portion of bottle 10 and prevents the coating 9from spreading to it.

FIG. 3 shows one embodiment of a coating machine in accordance with thisinvention, which enables continuous, economic coating of the bottles. Inview of the fact that bottles are inexpensive, mass produced, single usepackages, it is important to arrive at an embodiment which provides avery low cost operation, is compact (because preferred location isbeside a bottle blow molder), and is suitable for mass production (i.e.preferably continuous rather than batch processing).

In FIG. 3, the sequence of operation of the present invention isillustrated. Bottles or containers 10 will move through the variousstages A through H. Initially, the bottles are supplied via conveyor 39to a loading/unloading station 40. The bottles or containers 10 can befed immediately from a forming machine 29 to the coating system. Thisforming machine includes a blow molding machine, injection moldingmachine, extrusion molding machine or any other known machine forforming containers or bottles 10. As will be described below withreference to FIGS. 7A-7C, the surface of a PET bottle, for exampledeteriorates over time. If the containers or bottles 10 are quicklycoated after being formed, then potential obstructions to improvedadhesion on the surface of the bottles or containers 10 are absent.

From conveyor 39, an operator can manually move or other suitableequipment can automatically move the bottles or containers 10 to theloading/unloading station 40. The conveyor 39 can feed bottles from amolding machine or any other upstream process.

At the loading/unloading station 40, the bottles or containers 10 areplaced into or removed from a holder 41. This holder can have openinterior or it can have segmented sections for receiving individualbottles 10. The arrangement of the holder 41 will be discussed in moredetail below. The holder 41 used in FIG. 3 has four bottles in two rowsfor a total of eight bottles. Of course, this configuration could bemodified so as to meet the needs of the system.

The holder 41 with the loaded bottles or containers 10 can be manuallyor automatically moved from the loading/unloading station 40 at stage Ato the tool station 42 at stage B as noted above. The operation of thistool station 42 will be explained in more detail below with reference toFIG. 4. At this tool station 42, an antenna 30, cap 20 and anair-displacement collar 60 can be inserted into or removed from thebottles or containers 10. The cap 20, antenna 30 and collar 60 will becollectively designated as “tools”. The tools as well as the holder 41should be made of a non-gassing (low-absorbent) material whose surfacecannot damage the surface of the coated or uncoated bottles orcontainers 10.

From the tool station 42 at stage B, the holder 41 with the bottles orcontainers 10 can be manually or automatically moved into the evacuationcell 43 at stage C. Some door, air lock or other feature 56 is providedfor enabling a vacuum to be formed within the evacuation cell 43. Aswill be explained in more detail below, the displacement collar 60 whichhad previously been applied to the bottles or containers 10 can beremoved or reapplied in the evacuation cell 43. Also, a vacuum is eithercreated or released in this evacuation cell 43 as will be describedbelow.

From the evacuation cell 43, the holder 41 and bottles or containers 10move into the loading/unloading table 44 at stage D. Loading of thebottles from holder 41 to bottle-carrying bars 51 is carried out on thistable 44. Also, the bottles or containers 10 are unloaded from thebottles carrying bars 51 back into the holder 41 as will be described inmore detail below.

When the bottles or containers 10 are mounted on the bottle-carryingbars 51 at stage D, they are then passed to the degassing andpretreatment sections 45 and stage E. The antenna 30 which can be withinthe interior of the bottles or containers 10 will be oriented by amagnet 46 in the degassing and pretreatment sections 45. The bottles orcontainers 10 have their longitudinal axes generally vertically alignedwhen in the degassing and pretreatment sections 45 of stage E.

From the degassing and pretreatment sections 45, the bottles orcontainers 10 on the bottles carrying bars 51 will move to the basecoating section 47 at stage F. Then the bottles or containers 10 willmove the sidewall coating section 48 at stage G. It should be noted thatthe bottles or containers 10 move from a generally verticallyorientation in stage F to a generally horizontally orientation in stageG. This arrangement will be described in more detail below. From stageG, the bottles return to the loading/unloading table 44. The bottles orcontainers 10 are removed from the bottle-carrying bars 51 andreinserted into the holders 41. The holders 41 are then moved throughthe evacuation cell 43 at stage C to an intermediate holding position 49at stage H.

Now after this general description, a more detailed description of thearrangement of FIG. 3 will now be given. First, the bottles orcontainers 10 are loaded into holder 41 at stage A as noted above. Anoperator can manually insert the tools, cap 20, antenna 30 and collar60, onto the bottles or containers 10 or this step can be automaticallycarried out with appropriate equipment. This operation is carried out atthe tool station 42 at stage B.

When the holders 41 and bottles or containers 10 are moved into theevacuation cell 43 at stage C, a vacuum will be created in this cell 43.The collar 60 previously applied at tool station 42 during stage B willbe used to evacuate the interior of the bottles or containers 10 priorto the evacuation of pressure from cell 43. The purpose of collar 60 isreduce the amount of air brought into the evacuation cell 43. Togetherwith the holder 41 into which bottles or containers 10 tightly fit, thepre-evacuation of the containers or bottles 20 reduces the amount of airwhich must be evacuated from the cell 43. In other words, the bottles orcontainers 10 tightly fit into the holder 41. This holder 41 tightlyfits within the walls of the evacuation cell 43 in order to minimize theamount of air exterior of the containers or bottles 10.

Before or during insertion of the holder 41 with the bottles orcontainers 10 into the evacuation cell 43, the collar 60 is utilized toremove air from the interior of the bottles or containers 10. Therefore,the vacuum system for evacuating cell 43 need only evacuate the littleamount of air existing in the cells exteriorly of the containers orbottles 10. Therefore, the vacuum system capacity can be reduced. Thisis an important economic consideration in view of the low operatingpressure of the vacuum cell 50. This also helps to prolong the life ofthe vacuum system and helps to minimize the amount of energy consumedwith the instant system.

From the evacuation cell 43 at stage C, the holder 41 with the bottlesor containers 10 is moved to the loading/unloading table 44 at stage D.This loading/unloading table 44 is within the vacuum cell 50. The vacuumcell 50 and the evacuated cell 43 are both connected to a conventionalvacuum system (not shown). When the evacuation cell 43 reaches theappropriate pressure, various steps are undertaken including opening ofdoor 55 to permit entry of the holder 41 with the bottles or containers10.

Within the vacuum cell 50, the bottles or containers 10 are degassed andpretreated in section 45 at stage E. This degassing at stage E can takesixty seconds, for example. It should be noted that degassing of thecontainers or bottles 10 actually starts in the evacuation cell 43 atstage C. The degassing is completed during the pretreatment in section45 of stage E. The bottles or containers 10 are moved out of the holder41 at the loading/unloading table 44 and onto bottle-carrying bars 51which will be described in more detail below. The bottles are moved fromthe loading/unloading table 44 area in stage D to the subsequent stageswithin the vacuum cell 10 by movement of the bottle-carrying bars 51.

While a conveyor arrangement will described below for moving thesebottle-carrying bars 51, it should be appreciated that many differentarrangements could be used in order to convey the bottles or containers10 through the vacuum cell 50.

In the degassing and pretreatment sections 45, orienting magnets 46 canbe used to orient the antennas 11 or 30 as desired. The antennas couldbe stationary relative to a certain point on the container or bottles 10or can be movable relative to the bottles or containers 10. In thedegassing and pretreatment section 45 at stage E as well as in thedownstream base coating section 47 of the stage F, the bottles orcontainers 10 have their longitudinal axes vertically oriented.

In the pretreatment loading/unloading table 44 area at stage D or in thedegassing and pretreatment section 45 of stage E, heating of the bottlesor containers 10 can be carried out if appropriate. At these stages D orE or throughout the vacuum cell 50, radiant or infrared heaters (notshown) could be provided such that the bottles or containers 10 would beat an appropriate temperature. For example, this temperature could beambient to 60° C.

Apart from the bottles or containers 10 being at an appropriatetemperature to facilitate degassing, the antennas 11 or 30 with thecontainers can be used to accelerate the degassing as has previouslybeen noted. In particular, either RF or HR energy is applied to theinternal antenna 11 or 30. Alternatively, as noted with regard to FIG.1, a coating cell antenna 14 can be provided. DC/RF/HF energy can beapplied to this coating cell antenna 14 or from an infrared sourcelocated near the bottle surface 6. All of these features can acceleratedegassing. Also, the provision of a vacuum aids in the degassingprocess. It should be noted again that the antennas 11 or 30 insertedinto the bottles or containers 10 are also used in the pretreatmentsteps.

In particular, pretreatment is carried out either by using the in-bottleantenna 11 or 30 with RF or HF energy to create a gas-plasma on thebottle or container surface 6, or by connecting a coating cell antenna14 as shown in FIG. 1 to a DC or HF or RF source in creating a plasmawithin the entire cell 50. Alternatively, this cell 50 could besegmented into sections such that the plasma is only created in thedegassing and pretreatment section 45 of stage E. The pretreatment willlightly activate the surface of the bottle or container 10 in order toimprove the downstream coating. This pretreatment forms free radicals onthe surface 6 of the bottle or container 10 to assist in providingcontinuous coating and good adhesion leading to durable gas barriers.The pretreating step can last for 60 seconds, for example.

The bottle bars 51 holding the bottles or containers 10 can allow forrotation of the bottles through the degassing and pretreatment section45 of stage E. For example, the bottles or containers 10 could berotated at two revolutions per minute, for example. The RF bias used inpretreatment can be 700 volts with a 50 watt antenna. The gas within thedegassing and pretreatment section 45 of stage E is contemplated asbeing O₂ but any desired gas can be used. The gas flow will becontrolled so as to maintain correct pressure within the area ofdegassing and pretreatment section 45. This pressure can be 2×10⁻⁴ mbar.The duration could be, however, anywhere from 20-120 sec. with thebottles being rotated at 1-10 revolutions per minute. Also, the pressurecan be from 1-5×10⁻⁴. The flexibility in these ranges are given only asan example to indicate the required scope. For example, the pretreatmentduration can be achieved by varying the machine speed without anaccompanying change in machine size, whereby the accepted results wouldbe a change in output. Therefore great flexibility is obtainable withthe system of the instant invention.

The coating process is carried out in two parts. First, there was thepreviously noted base coating section 47 at stage F. Then the sidewallcoating section 48 at stage G completes coating of the bottles orcontainers 10. In this base coating section 47, the bottom or base ofthe bottles or containers 10 are coated. Then as will be described inmore detail below, the longitudinal axes of the bottles are changed fromthe vertical to a horizontal orientation. This is achieved by increasingspace between bottle bars 51. As will be described below with referenceto a fast-moving chain 53 and a slow-moving chain 52, this reorientationof the bottles or container 10 can take place. Throughout their verticaland horizontal orientations, the bottles or containers 10 are close toeach other to give best utilization to the evaporators or source 1, butthey do not touch. The bottles in the horizontal orientation are thenmoved through a sidewall coating section 48 at stage G. As the bottlesmove through the section, they can be rotated about their longitudinalaxis.

The bottles or containers 10 can be coated throughout movement in thesidewall coating section 48 or only in a portion thereof. The distanceof the coating section 48 over which the bottles are coated can beinfluenced by the amount of coating desired to be deposited on thebottles. For example, various sources 1 can be provided in the vacuumcell 50 for supplying the coating vapor to the bottles or containers 10.If a thicker external coating is desired, then more of the sources 1could be activated as opposed to when a thinner coating is desired. Ofcourse, other criteria can be modified in order to influence thethickness of the coating on the exterior of the bottles or containers10.

Similarly to the pressure in the degassing and pretreatment section 45of stage E, the pressure in both the base coating section 47 and thesidewall coating section 48 of stages F and G can be 2×10⁻⁴ mbar and canbe in the range of 1 to 5×10⁻⁴ mbar. It is contemplated that the basecoating in stage F will take 15 seconds but can be in the range of 10-30seconds. The sidewall coating in stage G can take 60 seconds but be inthe range of 20-120 seconds. The bottles will rotate two revolutions perminute in both sections 47 and 48 but can rotate from 1-10 revolutionsper minute. The bottle energy (RF-bias) will be 700 volts with a 50 wattantenna for at least the first 20% of the coating cycle. These numbersare merely given by way of example and can be varied.

Within the coating cell 50, an evaporator system can be provided. Thisevaporator system was described with reference to FIG. 1 and will alsobe described in more detail with reference to FIGS. 6A and 6B. Inparticular, evaporators or source 1 are provided in order to provide thecoating which will be deposited on the exterior of the bottles orcontainers 10.

The evaporators can be arranged in rows so that the evaporator fluxesoverlap their paths, giving an even longitudinal deposition rate R. Thisrate can be 3 nm/s and be in the range of 1-10 nm/s. The angle ofcontact α which was previously discussed therefore only applies to rowends and to the row cross sections where there is no overlap. This angleof contact α is indicated in FIGS. 6A and 6B and can be 30° or at leastin the range of 30-60°, for example. However, as previously noted thisangle should not be greater than 70°. This will help to enhance coatingadhesion.

It is desired that the evaporators layout must result in a minimumnumber of evaporators or sources 1 with the most effective use thereof.In other words, material loss should be minimized. The presentation ofbottle rows to the evaporator or source 1 can be four in a row asindicated in FIG. 3 but this number can be varied as desired. It ismerely desired that the evaporator or source 1 utilization will beoptimized.

As will be described below for FIGS. 6A and 6B, dust screens or shields93 can be provided. These shields or dust screens should be removableand easily cleaned. They will catch particles from the evaporator orsource 1 which are not flowing to the bottle surface.

In order to avoid the need for switching off the evaporators or sources1 during short cycle pauses, provision can be made for swing covers orsimilar covers to collect coating vapors during non-coating periods ofthe cycle. This will reduce the dust coating of the internal coatingcell. Automatic function controls and automatic detection ofmalfunctioning evaporators or sources 1 can also be provided. It isestimated that the parameters specified will result in a coatingthickness of about 50 nm. On this basis, the evaporation rate isestimated as follows. With the weight of the bottle being 30 grams andthe PET thickness being 0.35 mm, the coating thickness can be 50 nm.Therefore, the proportion coating to PET (V/V) will equal 0.00014. TheSi proportion of SiO₂ (W/W) will equal 0.467. The density of the SiO₂will be 2.5 with the density of PET being 1.3. Therefore, the weight ofSi of coating will be 0.004 g/bottle. At about 3,000 bottles per hour,the Si evaporated for bottle coating only (not including losses) will beabout 11.5 g with about 30 g/h including the total losses.

As has been described with reference to FIG. 1, the distance between theevaporator or source 1 and the bottle surface (H) can be 0.5 and be inthe range of 0.3 to 1 m. It should also be possible to remove sources 1from the vacuum cell 15 for inspection and/or maintenance withoutreleasing the coating or vacuum. A tandem evaporator system operatingthrough vacuum locks is one possibility. In view of this, no automaticmaterial feed to the evaporators would be needed. Of course, such anautomatic material feed could be used, if so desired. The evaporatingfunction must be monitored by instruments and can be visible fromoutside of the vacuum cell 50 by means of sight glasses, for example.

After moving through the sidewall coating section 48 at stage G, thebottles 10 will reenter the holder 41 at the loading/unloading table 44.This arrangement will be described in more detail with regard to FIG. 4.From the loading/unloading table 44 at stage D, the holders 41 with thereinserted bottles or containers 10 will back into the evacuation cell43 at stage C. Prior to moving into this evacuation cell 43, the collars60 will be placed on the containers at stage D.

When the holder 41 and bottles or containers 10 are reintroduced intothe evacuation cell 43, the vacuum can be released. Then, the holder 41containing the coated bottles or containers 10 will exit the evacuationcell 43. The holder 41 with the bottles 10 can then be slid to theintermediate holding position 49. At this position, the entry to theevacuation cell 43 will be clear such that another loaded holder 41 withuncoated bottles or containers 10 can be quickly reinserted into theevacuation cell 43. This helps to keep the continuous operation of thecoating system. After evacuation cell 43 is reloaded, the holder 41 canreturn to stage B whereat the tools are automatically or manuallyremoved. In other words, the cap 20, antenna 30 and collar 60 will beremoved from the bottles or containers 10. Then, at theloading/unloading station 40 at stage A, the coated bottles orcontainers 10 can be removed from the holder 41 and returned to theconveyor 39 for subsequent processing. New uncoated bottles orcontainers 10 can be placed into the emptied holder 41 enabling thedescribed cycle of operation to repeat.

When bottles 10 and holder 41 are viewed separately, bottles 10 firstpass through stages A to G, and then return through stages C to H to A.There are two holders 41, and these first pass through stages A to G,and return by passing through stages C to H to A. There are sufficientsets of tools to cover all bottles in stages B through H. The tools areapplied at stage B and return to stage B having passed through all thestages B to H.

Stages D, E, F, G are housed in a vacuum cell 50. Bottles 10 are grippedby bottle bars 51 and processed through the vacuum cell 50 by conveyorchains, one slow moving chain 52 and one fast moving chain 53. The slowmoving chain 52 pushes the bottle bars 51 in a closely packedarrangement, during the cycle of operations when the bottles 10 are heldin vertical position (for degassing and pretreatment at stage E and basecoating at stage F) and the fast moving chain 53 pushes the bottle bars51 with greater bar-to-bar spacing while the bottles 20 are in ahorizontal position (for sidewall coating at stage G). The bottle bars51 run in carrier rails 54 which firmly locate and carry the bottle bars51 as will be described in more detail with reference to FIG 5A.

The evacuation cell 43 is equipped with conventional mechanized doors 55which open/close to enable holder 41 to enter/exit. A ceiling door 55 ain FIG. 5 allows the collar 60 to be removed and/or reapplied) byconventional means prior to the holder 41 moving into the main sectionof vacuum cell 50. The compartment above the evacuation cell 53, wherethe collar 60 is held after removal, is part of vacuum cell 50, and boththis compartment and the main part of vacuum cell 50 are permanentlyunder vacuum. Evacuation cell 43 is evacuated to enable holder 41 toenter vacuum cell 50 and is returned to normal pressure to allow holders41 to exit the coating system.

Bottles 10 are conveyed conventionally along conveyor 39 to the coatingmachine (preferably directly from the blow molder), and to the bottlepalletizing system after coating.

FIG. 4 shows the handling of bottles 10 and tools. Bottles 10 enter aholder 41 at stage A. Bottles 10 fit tightly into cavities within theholder 41 to reduce the air gaps as much as possible, as this in turnreduces vacuum pump duty. At stage B, a collar 60 is applied to reducethe air gaps around the necks of bottles 10 and the antenna 30 and cap20 are fitted onto bottle 10. The caps 20 are screwed onto the bottles10 by a series of screw drivers which are part of a tool applicator 61.At stage C, the holder 41 enters the evacuation cell through door 55.Overhead door 55 a opens to allow collar 60 to be lifted off and storedin a storage compartment 62, within the vacuum cell 50. At stage D, theholder 41 is elevated to the bottle bars 51 which pick up the bottles 10by means of the snap-in connector 23 on the caps 20. The bottle bars 51now progress through the coating stages D to G.

After coating, the holder 41 is elevated at stage D to the bottle bars51 and the bottles 10 are released into holder 41. The holder 51 returnsto the evacuation cell 43, where the collar 60 is reapplied, and vacuumis released. Holder 41 exits to stage B, where the tool-applicator 61descends, grips caps 20 by the snap-in connector 23, unscrews caps 20and lifts caps 20, antennas 30 and collar 60 as a single unit, thecollar 60 being lifted off by the caps 20, which lock in its underside.The tool-applicator 61 and the quick release, screw driver devices,comprise conventional technology and will not be described further.

FIG. 5A shows details of the bottle bars, bottle turning and bottleconveying. Bottle bars 51 hold a plurality of bottles 10 in a row. InFIG. 5A, four bottles 10 are shown, as an example only. A bottle driveshaft 70 on which worm gears 71 are fitted, runs inside the bottle bars51, and is suspended by bearings 72 at each end of bottle bar 51. Thecap 20 acts as means for gripping the neck of the bottle or container 10to help hold it on bottle bar 51. As seen in FIG. 5B, this cap 20 alsocovers the neck and/or threads of the container or bottle 10 wherebycoating of this area of the container can be prevented. The bottle driveshaft 70, also shown in FIG. 5B, is driven by bevel gears 73, androtates by rotating the snap-in connectors 23 which are fitted with ascrew driver end piece (not shown) to thereby act as means for rotatingthe containers or bottles 10 during transport through the vacuum cell50. The bottle bar 51 is fitted at each end with carrier bars 74 inwhich it is free to swivel, due to bush bearings 75. The carrier bars 74are fitted with carrier wheels 76 which run in a pair of carrier rails54. The bottle bars 51 are conveyed by means of a drive chain 77, towhich a pall-finger 78 is attached which in turn impinges upon anextension arm 79 on carrier bars 74. The drive chain 77 is attached to amain shaft 80 which is driven by conveyor motor 81. A bottle rotationmotor 82 drives a bottle rotation sprocket 83 which is free to slideup/down main shaft 80 by means of bearing bushes 84. Bottle rotationsprocket 83 drives bottle rotation chain 85 which in turn drives thebevel gears 73.

The bottle bars 51 are attached to a guide wheel 90 which runs in aguide rail 91. This guide rail 91 is able to turn the bottle bar 51 froma position holding bottles 10 vertically (as shown) to a positionholding bottles horizontally by means of guiding the guide wheel up aramp 92 at the appropriate part of the conveying cycle. This switch froma vertical orientation to a horizontal orientation occurs between stagesF and G. When the bottles or containers 10 are horizontally oriented,the bottles or containers 10 continue to rotate without interruption bymeans of bevel gears 73 while the bottle rotation sprocket 83 moves upthe main shaft 80 to accommodate the new position of the bevel gears 73.Dust screens 93 previously noted protect the main parts of the drivesystem.

FIG. 6A is a view of bottle motion past source 1, both for base coatingand sidewall coating. Bottles 10 and caps 20 are held vertically in thebase coating section 47 by bottle bars 51 which continuously rotate boththe bottles 10 and caps 20. After base coating the bottles 10 are turnedto horizontal position for sidewall coatings as quickly as possible(i.e. with minimum gap between base coating section 47 and sidewallcoating section 48). The bottles are continuously rotating throughoutthe conveying cycle. Bottle bars 51 are designed compactly to minimizespacing between bottle rows in horizontal position. Sources 1 arepositioned so as to minimize the number of sources 1 needed andaccording to the criteria discussed in conjunction with FIG. 1, but withsome overlap as shown in FIG. 6B to ensure full coating coverage. Dustscreens 93, which are easily removable for cleaning, protect the machineparts from those deposits from source 1 which do not impinge on bottle10. Strip brushes with dust screens are used to separate, wheneverpossible, the main coating cell of vacuum cell 50 from the chains,motors, etc. used for transporting the bottle bars 51.

FIG. 9 is a graph showing improved barrier effect showing the importanceof coating composition to gas barrier. A small change in Zn compositioncan have a large effect on the barrier enhancement.

FIG. 10 is a flow chart illustrating a physical recycling process. Inrecycling, either physical recycling or chemical recycling are normallycarried out for plastic containers. In physical recycling, a batch ofplastic is provided as indicated in step 100. While this plastic caninclude a single type of item, it is contemplated that both coated anduncoated plastics will be provided. In a conventional process indicatedin step 102, these coated and uncoated plastics must be separated. Thiscan be a labor intensive step and will result in increased costs forrecycling.

With the instant invention, this separating step 102 can be avoided. Inparticular, step 104 indicates mixing of coated and uncoated containers.While this step can certainly be done at the recycling station, it iscontemplated that the actual mixing could take place prior to thearrival of the plastic at the recycling station. For example, when theplastic is picked-up by a refuse vehicle and taken to the recyclingcenter, such mixing could then occur. An advantage of the instantinvention is that when plastic to be recycled is mixed with coatedplastic being with non-coated plastic, separation of these two plasticsis unnecessary. In practice, this is, in fact, impracticable.Accordingly, when introducing coated containers into the recyclingsteam, the recycling process is unaffected.

As in a conventional process, the mixed plastics are ground into flakesin step 106. An optional step of washing the flakes 108 can be carriedout. In fact, a washing step could occur at many other times during theprocess.

After the step of washing 108, if it is carried out, or after the stepof grinding 106, the ground flakes are melt extruded at step 110. A stepof forming 112 then occurs which merely indicates that something is donewith the extrusion. For example, pellets, flakes or other configuredplastics could be melt extruded and then blow molded or injectionmolded. Many other uses for the recycled plastic are possible. The blowmolded or injection molded plastic can be reused for containers and inparticular, can be used for beverage containers. In fact, the batchplastic initially provided in the method at step 100 can be plasticbeverage containers whereby bottle-to-bottle recycling is possible. Ofcourse, the type of plastic handle and the output of the recyclingprocess is not limited.

Apart from the steps of physical recycling, the instant invention isalso applicable to a chemical recycling process as shown in FIG. 11.Again, plastics are provided in a step 114. Conventionally, a separatingstep 116 was necessary. The instant invention avoids such a separatingstep 116. Similarly to the above-described physical recycling, a mixingstep 118 for coated and uncoated plastic is indicated. This mixing cantake place at the recycling station or prior to the plastic's arrival atthis station.

In chemical recycling, the plastic is depolymerized by conventionalprocesses as indicated in step 120. To indicate the flexibility of theinstant invention, it is contemplated that separated coated and uncoatedplastic could be provided in the step 114. These separate plastics wouldbe separately depolymerized in step 120 but would be mixed together instep 122. This optional mixing step 122 is merely to indicate theflexibility of the instant invention.

After the plastic is depolymerized, it is repolymerized in step 124.This plastic can then be formed into a desired article such as by blowmolding or extrusion molding as indicated in step 126. Similarly to thephysical recycling process, the chemical recycling process can handleand produce many types of plastics. For example, bottle-to-bottlerecycling is possible.

Another benefit to the recycling process of the instant invention isthat haziness in the final recycled product is avoided. Becauserelatively small particles are used in the coating, a haze in thefinally produced recycled product can be avoided. Moreover, the coatingis acceptable for food contact and therefore will not adversely affectthe recycling efforts when ground or depolymorized in the recyclingprocesses.

The plastic produced in either recycling process can be injection moldedor blow molded as noted above. Even if a coated plastic is initiallyintroduced in the recycling process, the coating of the presentinvention will not interfere with the downstream injection molding orblow molding processes.

While the particular physical and chemical recycling have beendiscussed, it should be appreciated that the instant invention can alsobe applied in other types of recycling processes.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

We claim:
 1. A system for coating an external surface of a containerwherein the container on pressurization possess a gas barrier at least1.25×greater than a similar uncoated container, the system comprising: avacuum cell, pressure within the vacuum cell being reduced as comparedto ambient pressure; means for continuously supplying containers to andwithdrawing containers from the vacuum cell while maintaining thepressure within the vacuum cell; at least one source disposed within thevacuum cell for supplying a coating vapor to the external surface of thecontainers in the vacuum cell, the at least one source of coating vaporincluding an evaporator for heating and evaporating an inorganic coatingmaterial to form the coating vapor; and means for supplying at least onereactive gas to an interior of the vacuum cell; the at least one sourceof coating vapor structured and arranged within the vacuum housing suchthat the coating vapor from the at least one source reacts with thereactive gas and deposits a relatively thin coating on the externalsurface of the containers, the thin coating comprises an inorganiccompound, and bonding between at least a portion of the relatively thincoating deposited on the container and the external surface of thecontainer occurs.
 2. The system for coating as recited in claim 1,wherein the at least one source supplies the coating vapor from a solidsource.
 3. The system for coating as recited in claim 2, wherein thesolid source is a nonpowder.
 4. The system for coating as recited inclaim 1, wherein the means for causing coating causes at least one ofchemical bonding and physical bonding with the container.
 5. The systemfor coating as recited in claim 1, further including a plasma-enhanceddevice to provide means for causing the bonding.
 6. The system forcoating as recited in claim 1, further comprising a device for degassingthe containers prior to deposition of the relatively thin coating on theexternal surface of the containers, the degassing of the containersproviding means for causing the bonding.
 7. The system for coating asrecited in claim 1, wherein the container is a temperature sensitiveplastic bottle with a neck and wherein the system includes means forgripping the neck of the bottle.
 8. The system for coating as recited inclaim 1, further comprising means for rotating the containers duringtransport through the vacuum cell.
 9. The system for coating as recitedin claim 1, wherein the at least one reactive gas supplied by the meansfor supplying being selected from the group consisting of oxygen,nitrogen, sulfur and halogens.
 10. The system for coating as recited inclaim 9, wherein the at least one gas is oxygen.
 11. The system forcoating as recited in claim 9, wherein said gas and vapor from the atleast one source provide at least one of color coating for thecontainer, ultraviolet absorbent coating for the container and a gasbarrier for the container.
 12. The system for coating as recited inclaim 9, wherein said gas and vapor from the at least one source provideat least one of color coating for the container and ultravioletabsorbent coating for the container.
 13. The system for coating asrecited in claim 1, further comprising means for coating less than allof the external surface of the container by the coating vapor from theat least one source.
 14. The system for coating as recited in claim 1,further comprising a conveying device positioned within the vacuum cell,the conveying device moving the container through the vacuum cell pastthe at least one source.
 15. The system for coating as recited in claim1, wherein the container includes an interior chamber and wherein thesystem further comprises: an antenna insertable into and removable fromthe interior chamber of the container; and means for orienting theantenna when a longitudinal axis of the container is generallyhorizontally oriented.
 16. The system for coating as recited in claim 1,wherein the container includes an interior chamber and wherein thesystem further comprises: an antenna insertable into and removable fromthe interior chamber of the container; and means for orienting theantenna when a longitudinal axis of the container is generallyvertically oriented.
 17. The system for coating as recited in claim 1,further comprising an antenna provided within the vacuum cell.
 18. Thesystem for coating as recited in claim 1, further comprising means forgenerating a magnetic field within the vacuum cell wherein the fieldacts to direct the coating vapor.
 19. The system for coating as recitedin claim 1, wherein the at least one source supplies an inorganic vaporto the vacuum cell whereby the thin coating deposited on the containeris an inorganic solid coating.
 20. A system for coating an externalsurface of a container wherein the container on pressurization possess agas barrier at least 1.25×greater than a similar uncoated container, thesystem comprising: a vacuum cell, pressure within the vacuum cell beingreduced as compared to ambient pressure; means for supplying containersto and withdrawing containers from the vacuum cell; a conveying devicepositioned within the vacuum cell, the conveying device moving thecontainer through the vacuum cell past the at least one source; and atleast one source for supplying a coating vapor to the external surfaceof the containers in the vacuum cell, the coating vapor from the atleast one source depositing a relatively thin coating on the externalsurface of the containers whereby bonding between at least a portion ofthe relatively thin coating deposited on the container and the externalsurface of the container occurs, wherein the conveying device includes acontainer bar for holding the container, a slow-moving section and afast-moving section, the container bar being transferable between theslow-moving section and the fast moving section whereby the container onthe container bar can be moved at a first speed and then at a secondspeed through the vacuum cell, the first speed being slower than thesecond speed.
 21. The system for coating as recited in claim 20, furthercomprising means for rotating the containers during the transfer fromthe slow-moving conveyor to the fast-moving conveyor.
 22. The system forcoating as recited in claim 20, wherein the container has a longitudinalaxis and wherein the conveying device further includes means fororienting the longitudinal axis of the container vertically andhorizontally within the vacuum cell, the longitudinal axis of thecontainer being generally vertically oriented when the container isbeing moved at the first speed by the slow-moving section and beinggenerally horizontally oriented when the container is being moved at thesecond speed by the fast-moving section.
 23. The system for coating asrecited in claim 22, wherein the container includes an interior chamberand wherein the system further comprises an antenna insertable into andremovable from the interior chamber of the container and means fororienting the antenna to generally face the at least one source duringcoating.
 24. The system for coating as recited in claim 18, furthercomprising magnetic orientating means for orienting the antenna when thelongitudinal axis of the container is generally vertically oriented. 25.The system for coating as recited in claim 23, wherein the means fororienting includes a heavy section of the antenna which is rotatableunder the influence of gravity to face a bottom of the vacuum cell whenthe antenna and the longitudinal axis of the container are generallyhorizontally oriented.
 26. The system for coating as recited in claim23, wherein the antenna is pivotable toward and away from a wall of theinterior chamber of the container for facilitating insertion and removalof the antenna into and out of the container.
 27. The system for coatingas recited in claim 23, further comprising means for rotating thecontainer around the longitudinal axis of the container, the antennabeing within the container during rotation by the means for rotating andthe antenna being oriented within the container independent of rotationof the container.
 28. A system for coating an external surface of acontainer wherein the container on pressurization has enhancedenvironmental stress crack resistance, the system comprising: a vacuumcell, pressure within the vacuum cell being reduced as compared toambient pressure; means for supplying containers to and withdrawingcontainers from the vacuum cell; and at least one source disposed withinthe vacuum cell for supplying a coating vapor to the external surface ofthe containers in the vacuum cell, the at least one source of coatingvapor including an evaporator for heating and evaporating an inorganiccoating material to form the coating vapor; and means for supplying atleast one reactive gas to an interior of the vacuum cell; the at leastone source of coating vapor structured and arranged within the vacuumhousing such that the coating vapor from the at least one source reactswith the reactive gas and deposits a relatively thin coating on theexternal surface of the containers, the thin coating comprises aninorganic compound, and bonding between at least a portion of therelatively thin coating deposited on the container and the externalsurface of the container occurs.
 29. The system for coating as recitedin claim 28, wherein the at least one source supplies the coating vaporfrom a solid source.
 30. The system for coating as recited in claim 29,wherein the solid source is a nonpowder.
 31. The system for coating asrecited in claim 28, wherein the means for causing coating causes atleast one of chemical bonding and physical bonding with the container.32. The system for coating as recited in claim 28, further comprising aplasma-enhanced device to provide means for causing the bonding.
 33. Thesystem for coating as recited in claim 28, further comprising a devicefor degassing the containers prior to deposition of the relatively thincoating on the external surface of the containers, the degassing of thecontainers providing means for causing the bonding.
 34. The system forcoating as recited in claim 28, wherein the container is a temperaturesensitive plastic bottle with a neck and wherein the system includesmeans for gripping the neck of the bottle.
 35. The system for coating asrecited in claim 28, further comprising means for rotating thecontainers during transport through the vacuum cell.
 36. The system forcoating as recited in claim 28, wherein the at least one reactive gassupplied by the means for supplying being selected from the groupconsisting of oxygen, nitrogen, sulfur and halogens.
 37. The system forcoating as recited in claim 36, wherein the at least one gas is oxygen.38. The system for coating as recited in claim 36, wherein said gas andvapor from the at least one source provide at least one of color coatingfor the container, ultraviolet absorbent coating for the container and agas barrier for the container.
 39. The system for coating as recited inclaim 36, wherein said gas and vapor from-the at least one sourceprovide at least one of color coating for the container and ultravioletabsorbent coating for the container.
 40. The system for coating asrecited in claim 28, further comprising means for coating less than allof the external surface of the container by the coating vapor from theat least one source.
 41. The system for coating as recited in claim 28,further comprising a conveying device positioned within the vacuum cell,the conveying device moving the container through the vacuum cell pastthe at least one source.
 42. The system for coating as recited in claim28, wherein the container includes an interior chamber and wherein thesystem further comprises: an antenna insertable into and removable fromthe interior chamber of the container; and means for orienting theantenna when a longitudinal axis of the container is generallyhorizontally oriented.
 43. The system for coating as recited in claim28, wherein the container includes an interior chamber and wherein thesystem further comprises: an antenna insertable into and removable fromthe interior chamber of the container; and means for orienting theantenna when a longitudinal axis of the container is generallyvertically oriented.
 44. The system for coating as recited in claim 28,further comprising an antenna provided within the vacuum cell.
 45. Thesystem for coating as recited in claim 28, further comprising means forgenerating a magnetic field within the vacuum cell wherein the fieldacts to direct the coating vapor.
 46. The system for coating as recitedin claim 28, wherein the at least one source supplies an inorganic vaporto the vacuum cell whereby the thin coating deposited on the containeris an inorganic solid coating.
 47. A system for coating an externalsurface of a container wherein the container on pressurization hasenhanced environmental stress crack resistance, the system comprising: avacuum cell, pressure within the vacuum cell being reduced as comparedto ambient pressure; means for supplying containers to and withdrawingcontainers from the vacuum cell; a conveying device positioned withinthe vacuum cell, the conveying device moving the container through thevacuum cell past the at least one source; and at least one source forsupplying a coating vapor to the external surface of the containers inthe vacuum cell, the coating vapor from the at least one sourcedepositing a relatively thin coating on the external surface of thecontainers, whereby bonding between at least a portion of the relativelythin coating deposited on the container and the external surface of thecontainer occurs, wherein the for holding fast-moving transferable fastmoving container bar conveying device includes a container bar thecontainer, a slow-moving section and a section, the container bar beingbetween the slow-moving section and the section whereby the container onthe can be moved at a first speed and then at a second speed through thevacuum cell, the first speed being slower than the second speed.
 48. Thesystem for coating as recited in claim 47, further comprising means forrotating the containers during the transfer from the slow-movingconveyor to the fast-moving conveyor.
 49. The system for coating asrecited in claim 47, wherein the container has a longitudinal axis andwherein the conveying device further includes means for orienting thelongitudinal axis of the container vertically and horizontally withinthe vacuum cell, the longitudinal axis of the container being generallyvertically oriented when the container is being moved at the first speedby the slow-moving section and being generally horizontally orientedwhen the container is being moved at the second speed by the fast-movingsection.
 50. The system for coating as recited in claim 49, wherein thecontainer includes an interior chamber and wherein the system furthercomprises an antenna insertable into and removable from the interiorchamber of the container and means for orienting the antenna togenerally face the at least one source during coating.
 51. The systemfor coating as recited in claim 50, further comprising magneticorientating means for orienting the antenna when the longitudinal axisof the container is generally vertically oriented.
 52. The system forcoating as recited in claim 50, wherein the means for orienting includesa heavy section of the antenna which is rotatable under the influence ofgravity to face a bottom of the vacuum cell when the antenna and thelongitudinal axis of the container are generally horizontally oriented.53. The system for coating as recited in claim 50, wherein the antennais pivotable toward and away from a wall of the interior chamber of thecontainer for facilitating insertion and removal of the antenna into andout of the container.
 54. The system for coating as recited in claim 50,further comprising means for rotating the container around thelongitudinal axis of the container, the antenna being within thecontainer during rotation by the means for rotating and the antennabeing oriented within the container independent of rotation of thecontainer.